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Date:   Fri, 15 Sep 2023 19:50:01 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Pankaj Raghav <kernel@pankajraghav.com>
Cc:     linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        p.raghav@samsung.com, david@fromorbit.com, da.gomez@samsung.com,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        djwong@kernel.org, linux-mm@kvack.org, chandan.babu@oracle.com,
        mcgrof@kernel.org, gost.dev@samsung.com
Subject: Re: [RFC 00/23] Enable block size > page size in XFS
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References: <20230915183848.1018717-1-kernel@pankajraghav.com>
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On Fri, Sep 15, 2023 at 08:38:25PM +0200, Pankaj Raghav wrote:
> Only XFS was enabled and tested as a part of this series as it has
> supported block sizes up to 64k and sector sizes up to 32k for years.
> The only thing missing was the page cache magic to enable bs > ps. However any filesystem
> that doesn't depend on buffer-heads and support larger block sizes
> already should be able to leverage this effort to also support LBS,
> bs > ps.

I think you should choose whether you're going to use 'bs > ps' or LBS
and stick to it.  They're both pretty inscrutable and using both
interchanagbly is worse.

But I think filesystems which use buffer_heads should be fine to support
bs > ps.  The problems with the buffer cache are really when you try to
support small block sizes and large folio sizes (eg arrays of bhs on
the stack).  Supporting bs == folio_size shouldn't be a problem.